The present invention relates to an ink-jet printhead and a manufacturing process therefor, and more particularly to an ink-jet printhead, wherein the ink is supplied via an ink passage located in the central portion of the printhead, and a manufacturing process therefor, wherein the IC chip of the printhead can be prevented from cracking and a crack in the chip can be prevented from propagating when forming the ink passage by sand blasting so that the yield of the manufacturing process can be raised.
Ink-jet printers have been popular in recent years because of their fine printing quality, portable sizes, and fast printing speed with low noises.
In the present state of the art, an ink-jet printer typically comprises a thermal bubble type printhead or a piezoelectric type printhead. In a thermal bubble type printhead, a heating element is heated to reach a high temperature and cause a bubble generated in the ink instantly so that the pressure of the bubble ejects a small amount of ink. A piezoelectric type printhead uses a piezoelectric element that is responsive to the voltage applied on it and exerts a pressure on the ink through a thin film to eject the ink.
A conventional thermal bubble type printhead is provided with a plurality of ink ejection devices. Each of the ink ejection devices includes a heating element, an ink chamber, an ink ejection orifice, and a control unit. The control unit takes control of the heating function of the heating element so that a bubble of a predetermined size can be generated in the ink within the ink chamber when the ink is heated and a small amount of ink can be ejected from the ink ejection orifice for ink-jet printing.
For the thermal bubble type printhead, the heating elements and the conductive traces for connecting the control units are formed in or on a substrate so that control signals from the control units can be transmitted to the heating elements via the conductive traces for controlling ink-jet printing. Moreover, an ink chamber relative to each of the heating elements is formed in the substrate so that the ink within the ink cartridge can flow in the ink chamber of the printhead. An ink passage is formed in the central portion of the substrate by sand blasting. However, around the ink passage, there can be a crack or crack propagation incurred by sand blasting. This decreases the yield of the manufacturing process or affects the normal ink supply.
An object of the present invention is to provide an ink-jet printhead and a manufacturing process therefor so that when forming an ink passage in a substrate by sand blasting, the substrate can be prevented from cracking or a crack in the substrate can be prevented from propagating and thereby the yield of the manufacturing process can be raised.
Another object of the present invention is to provide an ink-jet printhead and a manufacturing process therefor so that the ink supply of the ink-jet printhead can be smoother over the prior art ink-jet printhead.
In accordance with the present invention, an ink-jet printhead and its manufacturing process are disclosed, wherein a substrate is provided and a loop-shaped protection layer of an appropriate size is formed on the central part of the substrate. The area surrounded by the loop-shaped protection layer is defined as an area for forming an ink passage through the substrate. An ink passage is formed on the predetermined area by sand blasting.
Just because of the loop-shaped protection layer formed beforehand, sand blasting on the area surrounded by the protection layer would not damage the substrate itself, and no cracking will be incurred. This results in high production yield, and moreover, this protection layer can be formed at the same time when forming the resistance layer, from which heating elements can be formed or the conduction layer by the photolithography, so the overall number of steps is kept the same.